THE parents of Brisbane journalist Peter Greste say they are enduring a "living nightmare" while he is locked in solitary confinement in an Egyptian maximum-security prison without charge.

His parents Juris and Loris Greste say the allegations against him are ludicrous and his detention, with two Al Jazeera English colleagues, since December 29 is unfair.

"To think or allege that Peter or his high-achieving colleagues would jeopardise their mid-life international careers by unethical or improper practices is completely preposterous," Mr Greste said during a media conference on Tuesday.

"It is absurd to think he would have any interest in serving groups which might be considered a threat to Egypt's security or deliberately misrepresent events as has been alleged.

"We wish the Egyptian people peace and prosperity however Peter's detention is most unfair and unjustifiable.

"Thus we respectfully but passionately ask the Egyptian prosecutor to free Peter and his colleagues immediately."

Though no charges have been laid, Mrs Greste said she understood the allegations to be broadcasting and using technical devices without a licence, falsifying information to insight and having connections with a banned organisation, specifically the Muslim brotherhood.

The Grestes said any suggestions their son was trying to destabilise Egypt were preposterous; describing Peter as a seasoned journalist who understood licensing, had won awards for his balanced journalism and upheld the highest principles of the industry.

Mr Greste - who apologised for weary eyes and a husky voice he explained came from three weeks without sleep - said the family was looking into a black hole when they tried to access information about the processes and procedures going forward.

"Although Peter has worked in challenging places and difficult circumstances we never expected that he'd be incarcerated just for doing what he loves," Mr Greste said.

"It horrifies me to read that some other Al Jazeera journalists were arrested months ago and they are still being held, we understand, without charges."

Mrs Greste said their son had a bed, wash basin and toilet in his cell where he was kept without release for 15 days but has since been allowed out four hours a day to exercise.

She said they had spoken to him three times when he was with the Australian consular representative and hoped to speak to him again when a review hearing is expected on Thursday (January 23).

"When you're a journo doing this sort of work, you've for to have a strong character and he's holding up very well," she said.

"We are holding up. We've got to because we can't let Peter down.

"It's shattering to the whole family and it's a living nightmare."

Mrs Greste said the Australian ambassador was trying to meet with the public prosecutor but had not yet been successful.

The award-winning journalist was arrested in his hotel room in Cairo with a producer and the bureau chief.

He is normally based in Nairobi, Kenya, for Al Jazeera Television's English service.

Peter, who always dreamed of becoming a foreign correspondent, was in Cairo on a three-week temporary placement, relieving another journalist, when he was arrested without charge.

He was raised and educated in Brisbane before working in various Australian cities and then knocking on the BBC's door to pursue his dream of becoming a foreign correspondent.

Since then Mr Greste has worked for ABC News, Reuters, CNN, BBC, WTN and Al Jazeera.

He won the Peabody Award for his documentary on Somalia in 2011

While there was a detectable sadness to their voices, the Grestes exhibited great determination and strength to fight for their son's freedom and uphold his reputation.